MQTT disconnects constantly

I am trying to do a very simple feature :
javascript(subscribe.js) -> aws iot (mqtt broker)

javascript(publish.js) -> aws iot (mqtt broker)

i am only trying to utilise teh mqtt broker capability of aws, that is , i am trying to use aws iot as an mqtt broker.
from the management console i am able to hold pub/sub.

PFB code for subscribe.js:

var awsIot = require('aws-iot-device-sdk');
// Replace the values of '<YourUniqueClientIdentifier>' and '<YourCustomEndpoint>'
// with a unique client identifier and custom host endpoint provided in AWS IoT.
// NOTE: client identifiers must be unique within your AWS account; if a client attempts 
// to connect with a client identifier which is already in use, the existing 
// connection will be terminated.
var device = awsIot.device({
    keyPath : 'secret.pem.key',
                certPath:'secret.pem.crt',
                caPath : 'rootCA.pem',
    clientId : 'id121',
    host : 'secret.iot.secret.amazonaws.com'
// Device is an instance returned by mqtt.Client(), see mqtt.js for full
// documentation.
device
  .on('connect', function() {
    console.log('connect');
    device.subscribe('topic_2/#');
device
  .on('message', function(topic, payload) {
    console.log('message', topic, payload.toString());
/*device
      .on('close', function() {
         console.log('close');
   device
      .on('reconnect', function() {
         console.log('reconnect');
   device
      .on('offline', function() {
         console.log('offline');
   device
      .on('error', function(error) {
         console.log('error', error);
      });*/
PFB code for publish.js:
var awsIot = require('aws-iot-device-sdk');
// Replace the values of '<YourUniqueClientIdentifier>' and '<YourCustomEndpoint>'
// with a unique client identifier and custom host endpoint provided in AWS IoT.
// NOTE: client identifiers must be unique within your AWS account; if a client attempts 
// to connect with a client identifier which is already in use, the existing 
// connection will be terminated.
var device = awsIot.device({
    keyPath : 'secret.pem.key',
                certPath:'secret.pem.crt',
                caPath : 'rootCA.pem',
    clientId : 'id121',
    host : 'secret.iot.secret.amazonaws.com'
// Device is an instance returned by mqtt.Client(), see mqtt.js for full
// documentation.
device
  .on('connect', function() {
    console.log('connect');
    //device.subscribe('topic_2/#');
    device.publish('topic_2/2', 'hello');
device
  .on('message', function(topic, payload) {
    console.log('message', topic, payload.toString());
device
      .on('close', function() {
         console.log('close');
   device
      .on('reconnect', function() {
         console.log('reconnect');
   device
      .on('offline', function() {
         console.log('offline');
   device
      .on('error', function(error) {
         console.log('error', error);
      });*/
Please help !!
thanks

Aarushi